1. Field of the Invention
The present invention relates to a process for hydrogenation of an organic peroxide to produce a mono- or polyhydric alcohol with a nickel catalyst wherein the catalytic activity of the nickel catalyst is maintained by improving the conditions under which the nickel catalyst contacts the organic peroxide.
2. Description of the Prior Art
It has been known that a mono- or polyhydric alcohol corresponding to an organic peroxide can be produced by contacting the organic peroxide with hydrogen in the presence of a neutral hydrogenation catalyst.
In the industrial operation of the reaction, the following two serious problems are encountered. One is the danger of explosion of the organic peroxide and the other is the poisoning of the hydrogenation catalyst. The present invention is concerned with preventing the poisoning of the catalyst.
Maintaining the catalytic activity of a nickel catalyst during the hydrogenation of an organic peroxide has been considered difficult because the poisoning of the nickel catalyst by the organic peroxide is very high. The severe poisoning of the nickel catalyst is clearly understood by the description of Example 3 of U.S. Pat. No. 2,879,306 wherein polymeric butadiene peroxide, an alternant copolymer of butadiene and oxygen, is hydrogenated to produce 1,2-butanediol and 1,4-butanediol. In order to hydrogenate only 6.5 g of polymeric butadiene peroxide, 0.5 g of Raney nickel catalyst (corresponding to 7.7 wt. % relative to the polymeric butadiene peroxide) is used in the first reaction step. It is shown that the catalytic activity of the Raney nickel is substantially lost just by using it in one partial hydrogenation.
Attempts have been made to reactivate the poisoned nickel catalyst used for the production of the corresponding mono- or polyhydric alcohol by contacting an organic peroxide with hydrogen in the presence of the nickel catalyst. (U.S. Pat. No. 3,896,051 and British Pat. No. 1,400,340). The properties of the catalyst poison in the hydrogenation of organic peroxides with nickel catalyst have been studied in the prior art.
The inventors have studied this process and found that in the hydrogenation of organic peroxides with a nickel catalyst, the poisoned nickel catalyst can be reactivated by contacting the catalyst with hydrogen at 140.degree. to 250.degree. C. in an oxygen-containing polar organic solvent which is resistant to hydrogenation. The inventors have further found that a suitable solvent for use in the reactivation is the reaction mixture resulting from hydrogenation of the organic peroxide. That is, it has been found that when an organic peroxide is contacted with hydrogen in the presence of a nickel catalyst to produce the corresponding mono- or polyhydric alcohol, the activity of the catalyst can be maintained for a long period of time by providing additional reaction time for reactivation of the poisoned catalyst after the point where no further increase in yield of the alcohol is observed, indicating the completion of the hydrogenation of the organic peroxide. The present invention has resulted from these discoveries and is not simply a specification of reaction conditions which are obvious over a conventional consideration to use a long reaction time for the hydrogenation of organic peroxides. In any event, it has not been known to be industrially advantageous to prolong the reaction after its completion, since the catalytic activity of the nickel catalyst can not be maintained for a long period of time solely by prolonging the reaction time if other essential conditions are not met.
The inventors have studied the poisoning of nickel catalysts used for the hydrogenation of organic peroxides to produce the corresponding mono- or polyhydric alcohols, and have found a novel process for hydrogenation of organic peroxides which is quite different from other processes for hydrogenation of compounds having carbonyl groups or unsaturated bonds.